1. Field of the Invention
The present invention relates to a rolling device in which two, inner and outer members that are disposed in a concentric manner are provided to be relatively displaceable through a plurality of rolling elements. The rolling device may be comprised by, for instance, a rolling bearing, a direct-acting type bearing or a ball screw device.
2. Description of the Related Art
Out of such rolling devices, those employed in a high vacuum environment such as in a delivery system disposed within a device for manufacturing semiconductors are required to exhibit especially strict specifications such as low dust-generating characteristics, smoothness of operation or high durability.
It is the case with conventional rolling devices that grease utilizing fluorine oil as base oil is sealed or fluorine oil is applied to portions at which rolling members perform rolling contact. Such fluorine oil does not include any functional groups in its molecular structure.
When utilizing such grease, external dispersion is coped with by decreasing the amount of sealed grease while such a measure may lead to lack in lubricating actions or degradations in durability.
When utilizing fluorine oil, it may similarly happen that lubricating actions fall short or the durability is degraded in case conditions in view of load or revolution speed become harder.
While it has already been devised to perform coating of fluorine high-molecular solid lubricants, such a measure is considered to provide insufficient durability causing peeling, dropout or increased generation of dust owing to wear in conditions in which relatively large axial load is applied.
It is a main purpose of the present invention to provide a rolling device that is capable of satisfying demands for achieving low dust-generating characteristics, smoothness of operation and improvements in durability.
Other objects, features and advantages of the present invention will become apparent from the following descriptions.
In summary, the two, inner and outer members that are disposed in a concentric manner are provided to be relatively displaceable through a plurality of rolling members.
A surface roughness of each rolling member is set to be smaller than a surface roughness of orbital planes the rolling members contact with each of the members.
Fluorine lubricating oil including a functional group in its molecular structure is adhered at least on the orbital planes in a manner as to fill each roughness of the orbital plane to extend from crest portions to trough portions.
In the present invention, a minimum amount of required lubricating oil exhibiting fluidity, which does not cause peeling, dropout or wear as it was the case with conventional solid lubricating oil, is adhered to the orbital planes that are defined to be of a specified roughness whereupon strong adsorption is achieved through bonding of the functional group within the lubricating oil with atomic chains on the surfaces of the orbital planes.
With this arrangement, metals are prevented from directly contacting each other during rolling operations of the rolling members and a condition is continuously maintained in which the lubricating oil does not fall short to thereby maintain stable lubricating actions.
The present invention is arranged in that the surface roughness of the orbital planes of the two members and the surface roughness of the rolling members are defined and their contacting conditions are controlled whereupon a minimum amount of required lubricating oil exhibiting fluidity, which does not cause peeling, dropout or wear as it was the case with coating films made of conventional solid lubricates, is adhered to the orbital planes through strong bonding force.
With this arrangement, contacting members will not come in contact with each other as metals without lubrication but will continuously contact each other with the lubricating oil being interposed between. Thus, it is possible to remarkably reduce the amount of generated dust and to remarkably improve lubricating properties and to therefore contribute to smoothness of operation and improvements in durability.